The present invention relates to a refractory plate assembly, particularly for use as a movable refractory plate in a sliding closure unit for regulating the discharge of molten metal from a metallurgical vessel.
Typically, this type of refractory plate assembly includes a refractory plate having therethrough at least one discharge opening and a metal jacket or sheath compression fitted around the peripheral surface of the refractory plate. This type of assembly however has certain inherent disadvantages. Thus, during use of the sliding closure unit the refractory plate is subjected to severe thermal stress. This results in the formation of cracks in the plate, particularly emanating outwardly from the discharge opening. The formation of such cracks inherently results in destruction of the plate.
Furthermore, the refractory plate has a planar sliding surface which abuts with a complementary sliding surface of a stationary refractory plate during use of the sliding closure unit. A portion of such planar sliding surface adjacent the discharge opening forms a closing surface area which is subjected to severe erosion by the molten metal during use. This requires that the refractory plate be replaced often or be formed entirely of a refractory material which is resistant to such erosion, and these types of resistant refractory materials conventionally are quite expensive.
Additionally known, for example from West German DE-OS No. 29 24 467, is a refractory plate assembly wherein the refractory plate is formed of plural portions separated by at least one separation joint or plane extending transversely of the discharge opening, the plural plate portions being held together by a metal jacket or sheath. Such German disclosure particularly shows a plate assembly having two discharge openings with two plate portions separated by a plane of separation passing through the two discharge openings, thus dividing the plate into two identical plate halves. This is done in order to facilitate easy replacement of hardening inserts or diaphragm inserts which are to be arranged in the discharge openings and which are formed of refractory materials which are particularly adapted to the respective casting or discharge conditions.